The National Weather Service said that rain enters the forecast for the holiday week, even until Christmas Day and can likely extend through the end of the year, SFGATE reported.

The weather service said two to three inches of rain is predicted to fall in urban places including Oakland and San Francisco between Monday and Dec. 26. North Bay’s coastal mountain ranges are forecasted to experience up to five inches of rain while the Santa Lucia Range in Big Sur and Santa Cruz Mountains could see up to six inches of rain.

“We already had a wet December and we’re looking to continue this pattern, probably close to the end of month,” weather service forecaster Brooke Bingaman said.

The wet week can be considered good news for the San Francisco Bay Area which was under a long period of dry season. Two straight dry winters have passed through the region and all of the state, making its water supply run low.

The rainy season is getting off to a wet start this year. According to weather service’s Brian Garcia, at least 200 percent of rainfall totals for this time of the year were recorded in the majority of the areas in the region since Oct. 1.

The first storm nears the region, bringing drizzle and light rain into the forecast Monday evening. The North Bay is expected to be hit first by the system on Tuesday morning until it eventually moves in the afternoon going South, according to Bingaman.

For Tuesday evening and Wednesday, many waves of rain are expected to continue.

“That first significant rain comes in Tuesday,” she explained. “Right now there is a low-pressure system that’s sitting out over the Pacific Ocean. It’s centered due west of the Oregon-California border. A low-pressure storm system rotates counter clockwise, and the moisture associated with that storm is going to rotate into California. That’s how we get several waves, the moisture rotates around it.”

Another system is forecasted to travel into the region from western Canada between Wednesday and Thursday. It will be absorbed by the first one, and through the weekend, rain can be expected.

“We’re in this trough pattern and it just keeps evolving and lingering all over the West Coast of North America,” Bingaman said.